Understanding Signals in Linux using C Language

In our previous tutorial, we introduced you to the concept of signals in Linux. Today, we will delve deeper into the world of signals and explore how they work in a Linux system using the C programming language.

What are Signals?

Signals are interruptions that can occur during the execution of a process. These interruptions can be generated by things outside the process, such as user input (like Ctrl+C from the terminal), or by errors inside the process itself (like a math error when dividing by zero).

The kernel handles signals in one of three ways: ignoring them, performing a default action, or executing a user-specified function. Signals can also be stored until they are ready to be handled.

Sending and Handling Signals

To send a signal to a specific process, we use the `kill` command with the `-s` option followed by the signal code. For example, if we want to send the signal `SIGUSR1` to a process with ID `PID`, we would run the command `kill -SIGUSR1 PID`.

In our C program, we can define a handler function for each signal code that we want to handle customly using the `signal()` function. We also need to include the `signal.h` library to use this function.

Using Switch Case Statements

The handler function can be the same and its behavior can change using a switch case statement that checks for the signal code. This allows us to define multiple signal handlers in a single program.

Examples and Applications

Signals are used in many real-world applications, including error handling and process control. For example, when you press Ctrl+C while running a command in the terminal, it sends the `SIGINT` signal to the process, which causes it to terminate.

In this tutorial, we will explore more examples of how signals can be used in Linux programming using C. We will also discuss how to install and use Signal Messenger on Linux Mint 21.

Signals are an essential concept in Linux programming, allowing us to handle asynchronous events and interruptions in our programs. In this article, we have explored what signals are, how they work, and how to send and handle them using the C programming language. Stay tuned for more tutorials on advanced Linux programming topics!

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